This invention relates to discrete particles that include a polymeric material, and articles formed from the discrete particles.
Conventional coated abrasive articles generally include a layer of abrasive grits adhered to a backing. Generally only a small fraction of the abrasive grits in this layer are actually utilized during the useful life of the coated abrasive article. A large proportion of the abrasive grits in this layer are wasted. Furthermore, the backing, one of the more expensive components of the coated abrasive article, must also be disposed of before it has worn out.
Many attempts have been made to distribute the abrasive grits on the backing in such a manner so that a higher percentage of abrasive grits are actually utilized, thereby extending the useful life of the coated abrasive article. By extending the life of the coated abrasive article, fewer belt or disc changes are required, thereby saving time and reducing labor costs. Merely depositing a thick layer of abrasive grits on the backing will not solve the problem, because grits lying below the topmost grits are not likely to be used.
Several methods whereby abrasive grits can be distributed in a coated abrasive article in such a way as to prolong the life of the article are known. One such way involves incorporating abrasive agglomerates in the abrasive article. Abrasive agglomerates consist of abrasive grits bonded together by means of a binder to form a mass. Abrasive agglomerates having random shapes and sizes are also known as well as precisely shaped abrasive agglomerates. Also known are precisely shaped particles of binder which are free of abrasive grits. There remains a need in the abrasive industry for thermosetting polymeric materials useful as binders to provide abrasive agglomerates with improved properties
In one aspect, the present invention provides a discrete particle including a polymeric material and a plurality of abrasive grits, wherein the polymeric material includes a reaction product of components including (a) an epoxy-functional material, and (b) at least one of a cyclic anhydride or a diacid derived therefrom. Preferably, the components further include (c) a polyfunctional (meth)acrylate.
In another aspect, the present invention provides a discrete particle including a plurality of abrasive grits and a polymeric material preparable by combining at least (a) an epoxy-functional material, and (b) at least one of a cyclic anhydride or a diacid derived therefrom. Preferably, the polymeric material is preparable by combining at least (a) an epoxy-functional material, (b) at least one of a cyclic anhydride or a diacid derived therefrom, and (c) a polyfunctional (meth)acrylate.
In another aspect, the present invention provides an abrasive article including a plurality of discrete particles that include a polymeric material including a reaction product of components including (a) an epoxy-functional material, and (b) at least one of a cyclic anhydride or a diacid derived therefrom. Preferably, the components further include (c) a polyfunctional (meth)acrylate. Preferably, at least a portion of the particles further include a plurality of abrasive grits. Preferably, the article further includes a backing and/or a nonwoven web attached to at least a portion of the particles.
In another aspect, the present invention provides an abrasive article including a plurality of particles including a polymeric material preparable by combining at least (a) an epoxy-functional material, and (b) at least one of a cyclic anhydride or a diacid derived therefrom. Preferably, the polymeric material is preparable by combining at least (a) an epoxy-functional material, (b) at least one of a cyclic anhydride or a diacid derived therefrom, and (c) a polyfunctional (meth)acrylate. Preferably, at least a portion of the particles further include a plurality of abrasive grits. Preferably, the article further includes a backing attached to at least a portion of the particles.
In another aspect, the present invention provides a method of preparing a discrete particle including combining at least (a) an epoxy-functional material, (b) at least one of a cyclic anhydride or a diacid derived therefrom, (c) a plurality of abrasive grits, and optionally (d) a polyfunctional (meth)acrylate to provide a composition; and at least partially curing at least a portion of the composition to provide a discrete particle. Preferably, the method includes irradiating at least a portion of the composition. Preferably, the method includes thermally curing at least a portion of the composition.
In one embodiment, the method of preparing a discrete particle includes providing a production tool having a three-dimensional body with one or more cavities in the three-dimensional body and introducing the composition into at least a portion of the one or more cavities. Preferably, the method includes partially curing at least a portion of the composition in at least a portion of the one or more cavities of the production tool. Preferably, the method includes removing the discrete particle from the cavity.
This invention makes it possible to design particles suitable for specific applications by varying the shape and composition of the particles.
Definitions
As used herein, xe2x80x9cbinder precursorxe2x80x9d means any material that is conformable or can be made to be conformable by heat or pressure or both and that can be rendered non-conformable by means of radiation energy or thermal energy or both. A binder precursor may include the polymeric material according to the present invention and optional materials including abrasive grits, fillers, and grinding aids.
As used herein, xe2x80x9cbinderxe2x80x9d refers to a solidified, handleable material. Preferably, the binder is formed from reaction of a binder precursor to provide a material (e.g., particles) that will not substantially flow or experience a substantial change in shape. The expression xe2x80x9cbinderxe2x80x9d does not require that the binder precursor is fully reacted (e.g., polymerized or cured), only that it is sufficiently reacted, for example, to allow removal thereof from the production tool while the production tool continues to move, without leading to substantial change in shape of the binder.
It should be understood that where incorporation of an ingredient is specified, either a single ingredient or a combination or mixture of materials may be used as desired. Similarly, articles including xe2x80x9ca,xe2x80x9d xe2x80x9can,xe2x80x9d and, xe2x80x9cthexe2x80x9d are meant to be interpreted as referring to the singular as well as the plural. It should also be understood that the specification of a value that includes the term xe2x80x9caboutxe2x80x9d is meant to include both higher and lower values reasonably close to the specified value. For example, for some properties values either 10% above or 10% below the specified value are intended to be included by use of the term xe2x80x9caboutxe2x80x9d.